The present invention relates to a child seat which is mounted and secured to a vehicle seat by a seat belt.
An example of this type of child seat has been disclosed in U.S. Pat. No. 5,839,789, herein incorporated by reference. FIG. 8 is a rear view of a child seat of U.S. Pat. No. 5,839,789, and FIG. 9 is a perspective view showing the structure for an adult seat belt winding mechanism at the bottom of the child seat.
The child seat 110 is mounted and secured to a vehicle seat (not shown) with an adult seat belt 100 (comprising a lap belt 100a and a shoulder belt 100b) of a vehicle and comprises a seat squab 112 on which a child is seated, a seat back 114, and a pair of dogleg-shaped side walls 116, 118 disposed on both sides of the combination of the seat squab 112 and the seat back 114. The dogleg-shaped side walls 116, 118 are provided with seat belt through apertures 120, 122, respectively, to allow the adult seat belt 100 to extend in the width direction of the child seat through these apertures 120, 122. The child seat 110 is also provided on the bottom thereof (the backside of the seat squab 112) with a wind-up reel 124 for winding the seat belt 100 extending between the seat belt through apertures 120 and 122 to tension the seat belt 100. The wind-up reel 124 has a slit 124a, for insertion of the seat belt, formed to penetrate the wind-up reel 124 in a diametrical direction. The slit 124a has a deep groove configuration extending in the axial direction of the wind-up reel 124 and exposed at one end of the axial direction.
The seat belt through apertures 120, 122 are formed in lower portions of the dogleg-shaped side walls 116, 118 to face each other such that the lap belt 100a composing the seat belt 100 extends substantially parallel to the top surface of the seat squab (not shown) of the vehicle seat when the lap belt 100a is threaded through one of the through apertures 120, 122 and is then threaded through the other.
The wind-up reel 124 is positioned halfway between the seat belt through apertures 120 and 122 such that the axial direction of the wind-up reel 124 is equal to the front-to-back direction of the child seat 110. The slit 124a is formed in the rear end of the wind-up reel 124. The rear end of the wind-up reel 124 is exposed at the seat back side of the child seat 110. In FIGS. 8 and 9, numeral 126 designates guide members for introducing the seat belt 100, inserted through the seat belt through apertures 120, 122, to the wind-up reel 124.
Integrally connected to the wind-up reel 124 is a torsion rod 128 which is disposed to extend along the bottom surface of the child seat 110 in the front-to-back direction. Secured to the front end of the torsion rod 128 is a worm wheel 130 which is meshed with a worm drive 134 described later.
A worm shaft 132 is disposed adjacent to the worm wheel 130 to extend in a width direction perpendicular to the axial direction of the torsion rod 128 and the wind-up reel 124. The worm drive 134 is fixed to the worm shaft 132 and is meshed with the worm wheel 130. The both ends of the worm shaft 132 penetrate the dogleg-shaped side walls 116, 118 so as to extend outside the child seat 110 through the right and left side walls 116, 118, respectively. The worm shaft 132 is provided at its both ends with knobs 136, 138 for operation of rotating the worm shaft 132 about its axis.
By the operation of rotating either of the knobs 136, 138, the wind-up reel 124 is rotated through the worm shaft 132, the worm drive 134, the worm wheel 130, and the torsion rod 128, whereby the seat belt 100 engaged in the slit 124a is wound around the wind-up reel 124. The worm gear composed of the worm wheel 130 and the worm drive 134 has a self-locking function. Therefore, even though the user looses his/her grip of the knob 136 or 138 after the seat belt 100 is wound around the wind-up reel 124, the wind-up reel 124 is stayed against the tension of the seat belt 100 by the self-locking function not to rotate in a direction opposite to the belt winding direction.
The child seat 110 is provided with clamps 140, 142 for clamping the seat belt 100 which are disposed on both lateral sides of the wind-up reel 124. Each clamp 140, 142 is adapted to allow the seat belt 100 to pass therethrough in a direction for winding up the seat belt 100 around the wind-up reel 124 and not to allow the seat belt 100 to pass therethrough in a direction opposite to the belt winding direction. Since the seat belt 100 is clamped by the clamps 140, 142, the seat belt 100 is prevented from being pulled out through the seat belt through apertures 120, 122 even when external force in a direction opposite to the belt winding direction is exerted to the seat belt 100.
A release lever 144 for releasing the clamping on the seat belt 100 by the clamps 140, 142 is provided at an upper portion of the seat back 114. The release lever 144 is interconnected to the clamps 140, 142 through a cable 146. As the release lever 144 is lifted, the respective clamps 140, 142 open to release the clamping on the seat belt 100. As the release lever 144 is depressed, the respective clamps 140, 142 close so that the seat belt 100 is clamped by the clamps 140, 142. In FIGS. 8 and 9, numeral 148 designates guide members for introducing the cable 146.
To secure the child seat 110 having the aforementioned structure to a vehicle seat, the release lever 144 is lifted into its open position to keep the clamps 140, 142 open. In this state, the seat belt 100 is threaded through one of the seat belt through apertures 120, 122 (in FIG. 8, the through aperture 122) and is threaded through the other through aperture 122 or 120 (in FIG. 8, the through aperture 120) so as to extend between the through apertures 120 and 122. Then, a tongue (not shown) is latched into a buckle (not shown).
The seat belt 100 extending between the through apertures 120 and 122 is inserted into the clamps 140, 142 and the halfway of the seat belt 100 is inserted into the slit 124a from the rear end of the wind-up reel 124. Then, the release lever 144 is depressed whereby the seat belt 100 is clamped by the clamps 140, 142.
After that, either of the knobs 136, 138 is turned to rotate the wind-up reel 124 so that the seat belt 100 is wound around the wind-up reel 124. Therefore, sufficient tension is applied to the seat belt 100, thereby firmly securing the child seat 110 to the vehicle seat.
When a three-point seat belt composed of a lap belt 100a and a shoulder belt 100b is used for securing the child seat 110 disclosed in U.S. Pat. No. 5,839,789, tension is applied to the shoulder belt 100b by winding up the shoulder belt 100b around the wind-up reel 124 so that the shoulder belt 100b tends to straighten between a deflection fitting and the tongue (both are not shown) to apply a raising force to the wind-up reel and the rear portion of the child seat 110 is thus biased upwardly.
Accordingly, there remains a need for a child seat which can be firmly secured to a vehicle seat even with a shoulder belt of a three-point seat belt.
In addition, in the child seat 110 disclosed in U.S. Pat. No. 5,839,789, it is difficult to recognize that sufficient tension has been really applied to the seat belt 100 by turning the knob 136, 138 to wind up the seat belt 100 around the wind-up reel 124.
Accordingly, there remains a need for a child seat which can wind up a seat belt to securely apply a predetermined tension to the seat belt.